Assessment of submicron bone tissue composition in plastic-embedded samples using optical photothermal infrared (O-PTIR) spectral imaging and machine learning.

Understanding the composition of bone tissue at the submicron level is crucial to elucidate factors contributing to bone disease and fragility. Here, we introduce a novel approach utilizing optical photothermal infrared (O-PTIR) spectroscopy and imaging coupled with machine learning analysis to assess bone tissue composition at 500 nm spatial resolution. This approach was used to evaluate thick bone samples embedded in typical poly(methyl methacrylate) (PMMA) blocks, eliminating the need for cumbersome thin sectioning.

Application of Optical Photothermal Infrared (O-PTIR) Spectroscopy for Assessment of Bone Composition at the Submicron Scale.

The molecular basis of bone structure and strength is mineralized collagen fibrils at the submicron scale (∼500 nm). Recent advances in optical photothermal infrared (O-PTIR) spectroscopy allow the investigation of bone composition with unprecedented submicron spatial resolution, which may provide new insights into factors contributing to underlying bone function. Here, we investigated (i) whether O-PTIR-derived spectral parameters correlated to standard attenuated total reflection (ATR) Fourier transform infrared spectroscopy spectral data and (ii) whether O-PTIR-derived spectral parameters, including heterogeneity of tissue, contribute to the prediction of proximal femoral bone stiffness.

Assessment of Porcine Osteochondral Repair Tissue in the Visible-Near Infrared Spectral Region.

Standard assessment of cartilage repair progression by visual arthroscopy can be subjective and may result in suboptimal evaluation. Visible-near infrared (Vis-NIR) fiber optic spectroscopy of joint tissues, including articular cartilage and subchondral bone, provides an objective approach for quantitative assessment of tissue composition. Here, we applied this technique in the 350-2,500 nm spectral region to identify spectral markers of osteochondral tissue during repair with the overarching goal of developing a new approach to monitor repair of cartilage defects .

Synovial joint cavitation initiates with microcavities in interzone and is coupled to skeletal flexion and elongation in developing mouse embryo limbs.

The synovial cavity and its fluid are essential for joint function and lubrication, but their developmental biology remains largely obscure. Here, we analyzed E12.5 to E18.

Nondestructive assessment of tissue engineered cartilage based on biochemical markers in cell culture media: application of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy.

Tissue engineering of cartilage for tissue repair has many challenges, including the inability to assess when the developing construct has reached compositional maturity for implantation. The goal of this study was to provide a novel analytical approach to nondestructively assess tissue engineered cartilage (TEC) during development. We applied attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to establish a quick and straightforward method to evaluate consumption of glucose and secretion of the metabolite lactate in the culture media, processes that are associated with tissue development.

Assessment of tissue damage from mosquito-inspired surgical needle.

Introduction: Many percutaneous procedures utilize surgical needles to extract tissue samples in biopsy or to apply specific cancer treatments. A design of mosquito-inspired surgical needles was proposed to improve the efficacy of these procedures by reducing the needle insertion force and the resulting tissue damage. The focus of this study is to assess tissue damage caused by the insertion of a mosquito-inspired needle into soft tissues.

Infrared Spectroscopy-Determined Bone Compositional Changes Associated with Anti-Resorptive Treatment of the Mouse Model of Osteogenesis Imperfecta.

Applications of vibrational spectroscopy to assess bone disease and therapeutic interventions are continually advancing, with tissue mineral and protein composition frequently investigated. Here, we used two spectroscopic approaches for determining bone composition in a mouse model () of the brittle bone disease osteogenesis imperfecta (OI) with and without antiresorptive agent treatment (alendronate, or ALN, and RANK-Fc). Near-infrared (NIR) spectral analysis using a fiber optic probe and attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) mode were applied to investigate bone composition, including water, mineral, and protein content.

Hesperidin Promotes Osteogenesis and Modulates Collagen Matrix Organization and Mineralization In Vitro and In Vivo.

This study evaluated the direct effect of a phytochemical, hesperidin, on pre-osteoblast cell function as well as osteogenesis and collagen matrix quality, as there is little known about hesperidin's influence in mineralized tissue formation and regeneration. Hesperidin was added to a culture of MC3T3-E1 cells at various concentrations. Cell proliferation, viability, osteogenic gene expression and deposited collagen matrix analyses were performed.

Characterization of Collagen Structure in Normal, Wooden Breast and Spaghetti Meat Chicken Fillets by FTIR Microspectroscopy and Histology.

Recently, two chicken breast fillet abnormalities, termed Wooden Breast (WB) and Spaghetti Meat (SM), have become a challenge for the chicken meat industry. The two abnormalities share some overlapping morphological features, including myofiber necrosis, intramuscular fat deposition, and collagen fibrosis, but display very different textural properties. WB has a hard, rigid surface, while the SM has a soft and stringy surface.

Applications of Vibrational Spectroscopy for Analysis of Connective Tissues.

Advances in vibrational spectroscopy have propelled new insights into the molecular composition and structure of biological tissues. In this review, we discuss common modalities and techniques of vibrational spectroscopy, and present key examples to illustrate how they have been applied to enrich the assessment of connective tissues. In particular, we focus on applications of Fourier transform infrared (FTIR), near infrared (NIR) and Raman spectroscopy to assess cartilage and bone properties.

Characterization of connective tissues using near-infrared spectroscopy and imaging.

Near-infrared (NIR) spectroscopy is a powerful analytical method for rapid, non-destructive and label-free assessment of biological materials. Compared to mid-infrared spectroscopy, NIR spectroscopy excels in penetration depth, allowing intact biological tissue assessment, albeit at the cost of reduced molecular specificity. Furthermore, it is relatively safe compared to Raman spectroscopy, with no risk of laser-induced photothermal damage.

MRI-derived porosity index is associated with whole-bone stiffness and mineral density in human cadaveric femora.

Ultrashort echo time (UTE) magnetic resonance imaging (MRI) measures proton signals in cortical bone from two distinct water pools, bound water, or water that is tightly bound to bone matrix, and pore water, or water that is freely moving in the pore spaces in bone. By isolating the signal contribution from the pore water pool, UTE biomarkers can directly quantify cortical bone porosity in vivo. The Porosity Index (PI) is one non-invasive, clinically viable UTE-derived technique that has shown strong associations in the tibia with μCT porosity and other UTE measures of bone water.

DMOG Negatively Impacts Tissue Engineered Cartilage Development.

Objective: Articular cartilage exists in a hypoxic environment, which motivates the use of hypoxia-simulating chemical agents to improve matrix production in cartilage tissue engineering. The aim of this study was to investigate whether dimethyloxalylglycine (DMOG), a HIF-1α stabilizer, would improve matrix production in 3-dimensional (3D) porcine synovial-derived mesenchymal stem cell (SYN-MSC) co-culture with chondrocytes.

Design: Pellet cultures and scaffold-based engineered cartilage were grown to determine the impact of chemically simulated hypoxia on 2 types of 3D cell culture.

Near infrared spectroscopic assessment of loosely and tightly bound cortical bone water.

Water is an important component of bone and plays a key role in its mechanical and structural integrity. Water molecules in bone are present in different locations, including loosely or tightly bound to the matrix and/or mineral (biological apatite) phases. Identification of water location and interactions with matrix components impact bone function but have been challenging to assess.

Approaches for Monitoring of Matrix Development in Hydrogel-Based Engineered Cartilage.

Near infrared (NIR) spectroscopy using a fiber optic probe shows great promise for the nondestructive monitoring of tissue engineered construct development; however, the NIR evaluation of matrix components in samples with high water content is challenging, as water absorbances overwhelm the spectra. In this study, we established approaches by which NIR spectroscopy can be used to select optimal individual engineered hydrogel constructs based on matrix content and mechanical properties. NIR spectroscopy of dry standard compounds allowed identification of several absorbances related to collagen and/or proteoglycan (PG), of which only two could be identified in spectra obtained from hydrated constructs, at ∼5940 and 5800 cm.

Clinical application of near infrared fiber optic spectroscopy for noninvasive bone assessment.

Approaches for noninvasive bone quality assessment are of great clinical need, particularly in individuals that require close monitoring of disease progression. X-ray measurements are standard approaches to assess bone quality; however, they have several disadvantages. Here, a nonionizing approach for noninvasive assessment of the second metacarpal bone based on near infrared (NIR) spectroscopy was investigated.

Fourier transform infrared spectroscopy of developing bone mineral: from amorphous precursor to mature crystal.

Bone mineral development has been described to proceed through an amorphous precursor prior to apatite crystallization. However, further analytical approaches are necessary to identify specific markers of amorphous mineral components in bone. Here, we establish an original Fourier transform infrared (FTIR) spectroscopy approach to allow the specific identification of the amorphous and/or crystalline nature of bone mineral.

MRI-derived bone porosity index correlates to bone composition and mechanical stiffness.

The MRI-derived porosity index (PI) is a non-invasively obtained biomarker based on an ultrashort echo time sequence that images both bound and pore water protons in bone, corresponding to water bound to organic collagenous matrix and freely moving water, respectively. This measure is known to strongly correlate with the actual volumetric cortical bone porosity. However, it is unknown whether PI may also be able to directly quantify bone organic composition and/or mechanical properties.

Environmentally-Controlled Near Infrared Spectroscopic Imaging of Bone Water.

We have designed an environmentally-controlled chamber for near infrared spectroscopic imaging (NIRSI) to monitor changes in cortical bone water content, an emerging biomarker related to bone quality assessment. The chamber is required to ensure repeatable spectroscopic measurements of tissues without the influence of atmospheric moisture. A calibration curve to predict gravimetric water content from human cadaveric cortical bone was created using NIRSI data obtained at six different lyophilization time points.

Ethics of Using Animal Models as Predictors of Human Response in Tissue Engineering.

Use of outcomes from animal research for prediction of human response in tissue engineering studies has many ethical considerations. This article aims to contribute to the ethical discussion by delineating the framework of animal research and the ethical considerations at play, in particular with respect to cartilage tissue engineering. The history of animal research regulation and the current status of animal research in orthopedic tissue engineering is discussed.

Spectroscopic Analysis of Human Tracheal Tissue during Decellularization.

Objective: To use mid-infrared (IR) spectroscopy to assess changes in the cartilaginous framework of human trachea during decellularization.

Study Design: Laboratory-based study.

Setting: Research laboratory.

Matrix mineralization controls gene expression in osteoblastic cells.

Osteoblasts are adherent cells, and under physiological conditions they attach to both mineralized and non-mineralized osseous surfaces. However, how exactly osteoblasts respond to these different osseous surfaces is largely unknown. Our hypothesis was that the state of matrix mineralization provides a functional signal to osteoblasts.

Infrared Spectroscopic Quantification of Methacrylation of Hyaluronic Acid: A Scaffold for Tissue Engineering Applications.

Methacrylated hyaluronic acid (MeHA) has been used extensively in tissue engineering and drug delivery applications. The degree of methacrylation (DM) of HA impacts hydrogel crosslinking, which is of pivotal importance for cell interactions. The methacrylation reaction occurs over several hours, and DM is currently assessed post reaction and after dialysis of the solution, using nuclear magnetic resonance (H NMR) data.

Spatial correlation of native and engineered cartilage components at micron resolution.

Tissue engineering (TE) approaches are being widely investigated for repair of focal defects in articular cartilage. However, the amount and/or type of extracellular matrix (ECM) produced in engineered constructs does not always correlate with the resultant mechanical properties. This could be related to the specifics of ECM distribution throughout the construct.

Validated Approaches for Quantification of Bone Mineral Crystallinity Using Transmission Fourier Transform Infrared (FT-IR), Attenuated Total Reflection (ATR) FT-IR, and Raman Spectroscopy.

Bone mineral crystallinity is an important factor determining bone quality and strength. The gold standard method to quantify crystallinity is X-ray diffraction (XRD), but vibrational spectroscopic methods present powerful alternatives to evaluate a greater variety of sample types. We describe original approaches by which transmission Fourier transform infrared (FT-IR), attenuated total reflection (ATR) FT-IR, and Raman spectroscopy can be confidently used to quantify bone mineral crystallinity.